Inhalable anesthetics (which are herein alternatively described as anesthetic agents) are typically volatile substances with relatively low boiling points and high vapor pressures. They can be flammable and explosive substances in both their liquid and vapor states. Further, inhalation of the vapor by health care personnel can cause drowsiness.
Therefore, such anesthetics must be safely handled in operating rooms in order to minimize the risk of inhalation by medical personnel as well as to minimize the risk of fire or explosion. Preferably, the anesthetic should be used in a way which will ensure that there is little or no release to the atmosphere at all stages of handling.
Anesthetics are typically dispensed in liquid form to an apparatus, such as an anesthetic vaporizer in an anesthesia machine. The vaporizer vaporizes the liquid anesthetic, and the anesthesia machine mixes the anesthetic vapor with oxygen and nitrous oxide. The mixture is supplied in gaseous form to the patient for inhalation.
Devices have been designed for the transfer of a liquid anesthetic from a supply container to a vaporizer through a closed system that minimizes the likelihood of the escape of an anesthetic liquid or gas to the atmosphere. The devices are designed so that during set-up and disassembly procedures, a supply container of anesthetic is not open and exposed to the atmosphere.
One system which has been developed for connecting an anesthetic container to a vaporizer is the QUIK-FIL.TM. vaporizer system sold by Abbott Laboratories, Inc., One Abbott Park Road, Abbott Park, Ill. 60064-3500, U.S.A.
The QUIK-FIL.TM. system includes a special filling inlet in an anesthetic vaporizer and includes a special mating anesthetic agent supply container having an opening through which the liquid anesthetic agent can be discharged. A valve member is provided in the container along with a first spring biasing the valve member to an extended, closed position occluding flow through the container opening. A container-receiving station or filling station on the anesthetic vaporizer defines the filling inlet and is adapted to matingly receive the container in an inverted orientation. The agent can be dispensed from the container into the filling inlet at the receiving station when the container valve member is automatically opened by proper engagement of the container by the receiving station structure.
In particular, a movable engaging member is provided on a valve inside the fill inlet in the receiving station along with a second spring for biasing the engaging member from a fully depressed, open position to an extended, closed position which seals the fill inlet closed. The engaging member is engagable with the container valve member and is urged to a fully depressed, open position when the container is inserted into the vaporizer receiving station. The second spring in the receiving station has less compression force than the first spring behind the container valve member so that the container valve member is moved away from the closed position by the engaging member in the filling inlet of the receiving station only after the engaging member has been first urged to the fully depressed, open position. The liquid agent can then flow from the container, past the open container valve member, through the vaporizer open valve, and into the vaporizer reservoir.
Some vaporizers are intended for use with only one specific anesthetic. In such situations, care must be taken to insure that only the proper anesthetic is dispensed into the particular vaporizer. To this end, the above-discussed QUIK-FIL.TM. filling system includes a keying system to prevent the use of the filling system with an anesthetic for which it is not designed.
In particular, the outlet end of the anesthetic container has projections of a specific shape, and the vaporizer fill inlet defines recesses having complementary shapes for mating with the container projections.
The above-described QUIK-FIL.TM. system is effective in transferring liquid anesthetic agent to the vaporizer. However, after the anesthetic has been administered to a patient or patients, some residual anesthetic may remain in the vaporizer. It is desirable to drain the residual anesthetic from the vaporizer. It is especially desirable to drain the vaporizer if the vaporizer is to be disconnected and removed from the anesthesia machine. If the anesthetic is drained from the vaporizer, then the vaporizer can be safely carried to another location for mounting to another anesthesia machine.
Heretofore, vaporizers have typically been emptied by opening a plug at the bottom of the vaporizer orifice and letting the anesthetic drain into an open receptacle or container held beneath the vaporizer. It would be desirable to provide an improved system for accommodating the draining of a vaporizer.
In particular, it would be desirable to provide a system for establishing a direct connection between the vaporizer drain and the receiving container. Further, it would be desirable to provide a system for assuring that the receiving container is securely maintained in a proper orientation without requiring that the container be held by an operator during the draining process.
It would also be advantageous to provide a draining system which could be readily used with an empty, or partly empty, container of the type used for filling the vaporizer. Preferably, the draining system should also accommodate containers of the self-closing type, and components of the draining system should preferably be readily connectable to such a container and should operate to readily open such a container upon establishing a proper connection.
It would also be desirable to provide a draining system which would be effective to prevent a vaporizer designated for use with one particular type or brand of anesthetic from being connected so as to drain into a container intended for another type of anesthetic. To this end, it would be advantageous to provide a draining system which would function only with the specific type of container that must be used to fill the vaporizer.
The draining system should also desirably function to minimize anesthetic waste through evaporation or anesthetic spillage, and minimize retention of residual transfer volumes of the anesthetic. Further, the draining system should preferably be very user friendly and should not interfere with the anesthesia machine operation.
When a vaporizer is disconnected and removed from an anesthesia machine, the vaporizer may be temporarily placed on a counter or table prior to, or after, transporting the vaporizer to another location. The vaporizer is typically disposed on its base in an upright orientation on such a counter or table--especially if there is residual anesthetic in the vaporizer. To accommodate this, it would be advantageous to provide a draining system that does not have stationary features projecting from, or below, the vaporizer base which would interfere with resting the vaporizer on its base.
Finally, it would be beneficial if the draining system could accommodate designs of components that are relatively inexpensive to manufacture.
The present invention provides an improved anesthetic draining system which can accommodate designs having the above discussed benefits and features.